Vyos to cisco GRE with ISIS

I am working on replacing some cisco routers with Vyos. One of the configs i’m working on that I can’t seem to get working is a GRE tunnel with ISIS runing on it. The GRE tunnel is up and working, but I can not get the ISIS to come up. From the cisco side it looks like a MTu issue, but can’t seem to get them to agree on a config. Any ideas or some place I can read up more on it? I am very new to Vyos.

Rec serial IIH from Tunnel (Tunnel1), cir type L1L2, cir id 00, length 1476
Sending serial IIH on Tunnel1, length 1513

set protocols isis interface tun0 network point-to-point
set protocols isis interface tun0 no-three-way-handshake
set protocols isis log-adjacency-changes
set protocols isis lsp-mtu ‘1473’
set protocols isis metric-style ‘wide’
set protocols isis net ‘49.0010.0023.2495.4a42.00’
set interfaces tunnel tun0 address ‘’
set interfaces tunnel tun0 encapsulation ‘gre’
set interfaces tunnel tun0 ip
set interfaces tunnel tun0 multicast ‘enable’
set interfaces tunnel tun0 remote ‘y.y.y.y’
set interfaces tunnel tun0 source-address ‘x.x.x.182’
set interfaces tunnel tun0 source-interface ‘eth2’

Version: VyOS 1.4-rolling-202201180317
Release train: sagitta

Built by: autobuild@vyos.net
Built on: Tue 18 Jan 2022 03:17 UTC
Build UUID: d50ca037-29e1-45b8-ac09-22e642ca4e97
Build commit ID: 52f75193f3afe7

Architecture: x86_64
Boot via: installed image
System type: bare metal

Hardware vendor: LENOVO
Hardware model: 10AAS3YH00
Hardware S/N: MJ02JLVN
Hardware UUID: 0b645448-0611-11e5-b2f5-780b77e81200

interface Tunnel1
ip address
ip mtu 1476
ip router isis
tunnel source GigabitEthernet0/3.2
tunnel destination x.x.x.182

router isis
net 49.0001.aaaa.aaaa.aaaa.00
metric-style wide
redistribute static ip

I think you have to use “gretap” as for ISIS you need Ethernet over gre

1 Like